If you’ll backup your library files so you have something to restore from, you can delete all of your smart playlists to see if there is any increase in performance on your computer.

Stated in a more technical way: I’m just kind of curious if the macros that are constantly running in the background to check songs to see if there have been any changes to the metadata impact how fast the system boots up, shuts down, or executes other commands such as adding a file to the library.

In my experience, whenever the status of a song changes – when you play it, rate it, change songwriter info, etc. – it moves into or out of the appropriate playlists. The only thing I can think of that would require the program’s self-monitoring would be my “Not Recently Played” list. However, not being a geek, I couldn’t state whether that would slow it down or not. For instance, it could just automatically update a playlist when you click on it.

(Short answer: I don’t know either. ) They sure let me get a lot more good out of my music than they did before I started using iTunes. I never get bored with my collection any more.